Merriam-Webster Collegiate Dictionary - occurrence

 noun  Date: 1539  1. something that occurs a startling ~  2. the action or instance of occurring the repeated ~ of petty theft in the locker room Synonyms:  ~, event, incident, episode, circumstance mean something that happens or takes place. ~ may apply to a happening without intent, volition, or plan an encounter that was a chance ~. event usually implies an ~ of some importance and frequently one having antecedent cause the events following the assassination. incident suggests an ~ of brief duration or secondary importance a minor wartime incident. episode stresses the distinctiveness or apartness of an incident a brief romantic episode in a life devoted to work. circumstance implies a specific detail attending an action or event as part of its setting or background couldn't recall the exact circumstances.